As an adult, Einstein did not possess a genius IQ. He nearly failed his college courses. And when he began writing the Generalized Theory of Relativity, he lacked the mathematical skills to complete the project. Eventually his former university colleague, Marcel Grossman, taught him how to use a form of differential geometry called tensor calculus to explain 4-dimensional space-time distortions. It was a slow and difficult process for Einstein, but he eventually prevailed in his endeavor to "generalize" all forms of motion on a macroscopic level.
Thats a myth he went to college studying advanced calculus
When Einstein was asked why this rumor got started he said it probably sounded inspirational to some people